Checkline DT-311J - Manual (Page 5)

(3) Power switch
(4) Connector
(5) Mode select switch
(6) Setting knob: for Flash Rate and Phase Shift adjustment
(7) Zero setting switch
(8) Divide ratio select switch
(9) Stroboscope flash: on/off switch
(10) Shift switch
4. CABLE CONNECTION
Connect power and signal with provided cable as follows:
AC plug (with 3-prong plug) 110 VAC or 230VAC at 50/60 Hz
Red clip Signal (positive)
Black clip 0V
5. MODE SELECTION
Press (MODE) switch (5) to select internal or external signal mode.